Conventionally, in a projection display device (hereinafter referred to as “projector”), e.g. a liquid crystal projector, light modulated by a light modulation element, e.g. a liquid crystal panel, is projected onto a projection surface by a projection lens. Examples of a light source include a lamp. When a lamp is used for an extended period of time, the lamp deteriorates. Thus, after having reached its end of life, the lamp needs to be replaced with a new one.
A projector main body can include apertures through which respective lamps are taken in and out. In this case, each lamp aperture is covered with a corresponding cover. When replacing a lamp, the user opens the cover and takes out the lamp.
In such a projection display device, generally, a lamp is replaced only when the operation is stopped. Thus, when the cover is opened during the operation, the lamp is turned off and thereafter the operation is stopped. Also, when a lamp overheats during the operation or the driver for driving the lamp does not operate normally, the lamp is turned off and thereafter the operation is stopped. That is, opening of the cover is handled as an abnormality similar to abnormal temperature of the lamp and abnormal operation of the lamp driver. Thus, the same operation, i.e. stopping the operation, is performed.
In order to increase the intensity, such a projector can be configured so as to include a plurality of lamps, which is called a multi-lamp configuration (see Patent Literature 1, for example). In a multi-lamp projector, when the end of life or a failure makes one lamp unlit, the intensity of an image decreases, but the operation can be continued with the remaining lamps in operation. Thus, the multi-lamp projector can be configured such that an unlit lamp can be replaced not when the operation is stopped as described above, but while the operation is continued.